The present disclosure is directed to the configuration of a fuel rail for a fuel injection system of an internal combustion engine. In particular, the present disclosure is directed to an improved fuel rail geometry that minimizes fluid pressure pulsations within the fuel rail system.
It is believed that it is desirable for fuel injection systems to insure that the fuel is evenly distributed to each cylinder of a multi-cylinder engine. It is believed that a fuel rail distributes to plural fuel injectors the fuel that is supplied from a fuel tank. It is believed that these fuel injectors can be operated in response to electrical signals from an engine control unit, and that the fuel required for combustion is sprayed out of the injector, into either an intake manifold or directly into a combustion cylinder.
It is believed that an adequate supply of fuel for all the injectors can be provided via a fuel rail having a large enough capacity to ensure that sufficient fuel is available at all times to the fuel injectors. It is further believed that a so-called xe2x80x9creturn systemxe2x80x9d feeds fuel in excess of that required by the fuel injectors back to the fuel tank via a return line. It is believed that the excess fluid is heated as a result of being circulated through the engine compartment, and that this heating can adversely affect the control of emissions from the fuel system.
It is believed that adequate fuel pressure for each fuel injector can be provided with a pressure-regulating device connected downstream of the fuel rail. When fuel pressure in the fuel rail is above a certain set point, it is believed that the pressure-regulating device opens to allow the excess fuel to be returned to the fuel tank via the return line, thus controlling pressure in the rail. When fuel pressure in the fuel rail is below the set point, it is believed that the pressure-regulating device is closed to allow pressure to build up in the fuel rail. It is believed that some pressure-regulating devices are operated using a vacuum bias tube that is coupled to the engine intake manifold.
It is believed that there are a number of deficiencies and disadvantages that are associated with know xe2x80x9creturnxe2x80x9d fuel systems, which has led to the development of a xe2x80x9cnon-returnxe2x80x9d fuel system. It is believed that non-return fuel systems include a pressure-regulating device that is placed closer to the fuel tank, and that a return line from the fuel rail to the fuel tank is eliminated. Is believed that by virtue of the pressure being regulated upstream of the fuel rail, there is no excess pressure/fuel that is returned to the fuel tank after having been circulated through the engine compartment. It is believed that xe2x80x9cnon-returnxe2x80x9d systems provide improved emissions control and reduced cost. However, it is believed that xe2x80x9cnon-returnxe2x80x9d systems experience fuel pressure pulsations in the fuel rail.
It is believed that there is a need to provide a non-return fuel system that minimizes the fluid pressure pulsations in the fuel rail.
The present invention provides a fuel rail for a non-return fuel injection system. The system includes a source of pressurized fuel and at least one fuel injector. The fuel rail comprises an inlet, at least one first outlet, and at least one tube providing fluid communication between the inlet and the at least one outlet. The inlet is adapted for fluid communication with the source of pressurized fuel. The at least one first outlet is adapted for fluid communication with a respective fuel injector. The at least one tube extends along a first axis and includes a first portion and a second portion. The first portion extends a first length along the first axis and has a first cross-sectional shape transverse to the first axis. The second portion extends a second length along the first axis and has a second cross-sectional shape transverse to the first axis. The second cross-sectional shape has a first indentation toward the first axis, and the first indentation disrupts pressure pulsations propagating through the at least one tube.
The present invention also provides a method of of reducing pressure pulsations in a non-return fuel injection system. The pressure pulsations arise as at least one fuel injector discharges fuel and a source of pressurized fuel replenishes the fuel available to the at least one fuel injector. The method comprises providing a fuel rail and indenting the fuel rail to disrupt the pressure pulsations. The fuel rail establishes fluid communication between the source of pressurized fuel and the at least one fuel injector. The fuel rail extends along an axis. The indenting includes providing the fuel rail with different transverse cross-sections along the axis.